1. Field of the Invention
The present invention relates to an electronic document conversion device and an electronic document conversion method for converting an electronic document to an electronic document in a different format. More particularly, the invention relates to an electronic document conversion device and an electronic document conversion method for correctly inheriting a security policy such as “password”, “print permission/inhibition”, or “character extraction permission/inhibition”.
2. Description of the Related Art
In recent years, use of an electronic document that can be read or edited on a computer has spread, where a PDF, an HTML, a JPEG and an XPS are well known as representative electronic document formats. To peruse or edit an electronic document of these formats, a viewer program or an editor program is required, but the viewer or editor for each of the electronic document formats is not necessarily installed in every computer. Also, there is a document management system for managing an existing electronic document corresponding to a paper document by conversion into its own electronic document format (refer to Japanese Patent Laid-Open No. 2001-216230). For the above reason, the conversion between different electronic document formats is indispensable.
Also, a security policy (rule of security) can be set in a relatively new electronic document format represented by the PDF, with a function of imposing a limitation on the functions of edit/perusal/print/character extraction according to the security policy. This is an important function for preventing falsification of electronic documents or leakage of information.
The security policy should be inherited even upon conversion into another electronic document policy, to fulfill its purpose (prevention of falsification or prevention of information leakage). However, there are electronic document formats without any security policy. In such electronic document formats, there is a problem that if, for example, a PDF file with print inhibition set is converted into the HTML or JPEG format in an electronic document conversion system, the file becomes printable.
Also, among electronic documents supporting a security policy, the specifications for the security policy are different for each electronic document format. For example, consider a case where an electronic document in a format in which the character extraction inhibition can be set for each character string or each area is converted into another electronic document format (e.g., PDF) in which the character extraction inhibition can be set only for characters. In this case, there is a problem in that the setting of the character extraction inhibition for each character string or each area is canceled.